Water heater



FIG. 1 is a side elevational, perspective view of a water heater showing my new design;

FIG. 2 is a side elevational view thereof;

FIG. 3 is a side elevational view of the side thereof opposite to that of FIG. 2;

FIG. 4 is a top plan view thereof the bottom view being a mirror image; and,

FIG. 5 is a left elevational end view thereof, the right end elevational view being a mirror image thereof. 

The ornamental design for a water heater, as shown and described. 